Data Inversion for the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC)

After launch in late 2005 the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) is expected to monitor Earth's atmosphere from orbital altitude ~800 km to near the surface with high vertical resolution about 2500 times a day. COSMIC inversion software is based on advanced algorithms and data quality checks. It starts with filtering of raw data and detection of obvious tracking errors. In the lower troposphere, under conditions of multipath propagation, the bending angle as function of impact parameter is calculated by radio- holographic methods such as Full Spectrum Inversion. Ionospheric calibration is applied for L1 and L2 bending angles above the lower troposphere and is extrapolated below. For retrieval of refractivity, the ionospheric free bending angle at high altitudes is subject to optimal estimation by use of climatology as the first guess. Refractivity is retrieved from the optimized bending angle by Abel inversion. The retrieved profiles of refractivity and bending angle are accompanied by a number of scalar parameters characterizing their quality in different respects and allowing selection of different occultations for different purposes. For example, the occultations with low effect of random ionospheric irregularities can be selected for stratospheric monitoring. Special attention has to be paid to truncating the data below the top of planetary boundary layer to avoid biases due to superrefraction. A series of tests will be performed with the open loop radio occultation data. To reduce the effect of horizontal refractivity gradients in the moist troposphere, when assimilating radio occultation data, a simple non-local linear observation operator has been developed. This talk will provide an update of data inversion system that is under development for COSMIC.